Title: Probing Cosmic History and the Hubble Constant via Gamma-Ray Attenuation Speaker: Prof. Alberto Dominguez (Universidad Complutense de Madrid) Date: 2026-10-14 • 15:00 PM Location: Sala 201 (M15)

Abstract: The light emitted by all galaxies across cosmic time is encoded in the extragalactic background light (EBL), the diffuse background spanning ultraviolet to infrared wavelengths. Through electron positron pair production, the EBL acts as a source of opacity for very-high-energy gamma rays, leaving a distinct attenuation imprint on the spectra of distant sources. In this seminar, I will report on new EBL measurements derived from both the Fermi Large Area Telescope and ground-based Imaging Atmospheric Cherenkov Telescopes. These measurements allow us to constrain the cosmic star formation history and provide an independent measurement of the Hubble constant and cosmic matter density. These results demonstrate that high-energy astrophysics provides competitive cosmological constraints complementary to traditional astronomical surveys.

Read more: https://weiguangcui.github.io/DECAF/blog#2026-10-14